This invention relates to a novel X-ray detector and more specifically relates to a novel wide area X-ray detector for providing the amplified optical image of an X-ray image.
X-ray detectors are well known and are generally divided into two categories: scintillographic devices or charge transfer devices.
Scintillographic devices, such as X-ray image intensifiers are well known and are the basic devices in use in most hospitals. The operation of the conventional X-ray image intensifier involves multiple energy level transitions, coupled with a sophisticated electronic lens accelerator to provide high gain. The primary limitations of this device revolve around the necesary trade-offs that relate to the quantum detection efficiency of the scintillator, the spatial resolution, the contrast detectability and the system modulation transfer function (MTF).
Charge transfer devices commonly use the principle that energetic X-ray photons will deposit their charge directly onto a detector structure where the charge is directly accessible as an electrical signal. Charge transfer devices are more difficult to fabricate than scintillographic detectors, but offer significantly higher gain, spatial resolution and contrast detectability. The detector structures consist, for example, of an array of PN junctions in a semiconductor substrate with appropriate physical characteristics for the frequency band to be detected.
The present invention provides a novel X-ray detector which offers the general simplicity of X-ray image intensifiers and the high gain resolution and contrast which is available with charge transfer type devices.